In the manufacture of vacuum cleaner filter bags that are inserted into a vacuum cleaner and that are intended to hold the dust that is suctioned in, one of the main focuses of the development is to increase the dust-holding capacity and service life. To accomplish these, there are different approaches that concern the filter structure, i.e., the configuration of the filter material layers of the bag wall and/or the parameters of the individual layers themselves.
For example, EP 0 960 645 exhibits a multi-layer filter configuration in which a coarse filter layer is arranged before a fine filter layer, as seen in the direction of flow. In particular, larger quantities of dust are intended to be deposited in the coarse filter layer, which prevents the entire filter structure from becoming quickly blocked.
A further possibility is defined in WO 2005/060807, according to which a vacuum cleaner filter bag contains a material that can be swirled around in the presence of a given air flow.
From DE 10 2006 016 009, a vacuum cleaner filter bag with a deflective device is known by means of which the service life can likewise be significantly increased.
Another focus during the enhancement of vacuum cleaner filter bags consists of the suppression of the formation of unpleasant smells and/or bacteria growth for reasons of hygiene. In this connection, DE 20 2005 009 452 describes a vacuum cleaner bag, whereby one of the items arranged inside is a biocide. In particular, plant parts+powders of, e.g., chamomile, thyme or oregano are mentioned for this. Complete plant parts are not fibrous by nature and cannot be processed into nonwovens. In addition to active components, plant parts also contain high proportions of builders that reduce the effectiveness (dilution effect).
Known from DE 29 11 004 is a filter bag which has a coating with a nonwoven on its interior side, whereby said nonwoven is provided with antimycotic or antibacterial agents. Various synthetic substances are used thereby as antibacterial and antimycotic agents.
The disadvantage of a filter bag of this type lies in the fact that the use of synthetic bactericides and fungicides is ecologically and economically problematic. The active substances are expensive and frequently cause allergic reactions. The manufacturing processes for the filter bag are further complicated by the additional layer, and the filter characteristics of the filter bag also change unpredictably, because, in particular, the oily biocides can influence the characteristics of the successive filter layers. For example, the persistence of an electrostatic charge of a nonwoven is reduced by contact with oily substances.